My trailer this year has sure been a PITA. I had the Ďsurge brake actuatorí replaced this Spring, and now Iím replacing all four tires.

I did a rough estimate. With 280 hours on a 2006 boat bought new (and guessing 120 trailer miles for every 5 boat hours), I did not get 7,500 miles on these parts nor 75 launches.

I think I should have gotten better ... a lot better !!! Anyway, as I did not, attached below are some pics of the replaced surge brake actuator Ė just because in my time on this board Iíve never seen another pic of any, and it is a curious chunk of metal. I bet this could be re-furbished.

alans

08-30-2010 8:45 AM

Why does the solenoid look melted?

newty

08-30-2010 9:03 AM

Alan, I'll bet its just the paint bubbling off from the brake fluid leaking.

John what failed? You sure you don't just have a leak and emptying the resivoir?

alans

08-30-2010 9:08 AM

Good call on the paint. Yea, I want to know what failed? Everything looks good in the pics.

helinut

08-30-2010 9:39 AM

Funny to see this here this morning. I was just working on mine last night. I had to bleed the brakes like crazy. I'm now doubting my brakes ever worked from the day I picked the boat up 3 years ago. There was a bunch of air in the lines. They work now though! I need to take it out to see what it feels like to have trailer brakes.

The main parts are a master cylinder, a shock, spring and a reversing solenoid. There are several small parts in there but they're relatively inexpensive. If it's well worn it's about the same price to replace the whole thing if you're looking at replacing the shock and the master cylinder plus a few small parts.

I was 90% sure mine was bad but didn't feel like spending the money. The reservoir was full of rust so I flushed it out with clean brake fluid. Sucked the old stuff out with a syringe the put new stuff in. Sucked the new stuff out and replaced it about 10-15 times until the fluid came out looking almost clear. Then I bled the brakes with a power bleeder several times. After that the brakes actually work and the actuator is 10 years old.

Jeff

08-30-2010 9:48 AM

Also, I would expect the actuator to last for years and tens of thousands of miles if used in fresh water and the fluid is changed regularly.

john211

08-30-2010 9:49 AM

My dealership and myself never made a definitive determination what was wrong. But the problem denied my the first 3 trips of the year. So I had it replaced.

Evidently, the trailer brakes were constantly applied. I would accelerate up to 35 mph or so, and the trailer brakes would heat up and brake so hard as to pull me down to a creep, then a stop.

While the brakes were hot, the dealership could jack up the trailer and show to itself and to me that all 4 trailer tires were locked (to being spun by hand, but it was possible to push or pull with the tow vehicle and they might (or might not) spin ... and if they did spin, the brakes were still applied then too).

When the brakes would cool down (say, next morning), the dealership by tractor could push and pull the trailer (real slow) without the problem repeating. And so I’d set off again for a next trip, and same problem. I never got a quarter mile away. The last time for me, the dealership came out to the side of the highway, and bled the brake fluid off. That let me return to the dealership with actuator disabled.

They guessed at the time that it was something between the cylinder and the solenoid. We reviewed options of servicing one, the other or both of the cylinder and solenoid ... versus complete replacement. Being impatient to get out on the water, I just had it replaced.

I gotta get to work. I cannot return for a day or two now. But I might check that paint on the solenoid and see if it looks heat melted or chemically attacked.

Jeff

08-30-2010 10:04 AM

It definitely looks like the brake fluid just ate the paint.

Brakes locking can be water in the system. The water sits in there and works similar to brake fluid when everything's cool. Then things get hot and the brakes start working and the water boils. Water turns into seam at a rate of something like 10,000:1 at atmospheric air pressure. So, the steam effectively applies the brakes by artificially increasing pressure in the braking system.

alans

08-30-2010 11:13 AM

Nice ^^^ Jeff knows his brakes. Not many other possibilities, hydraulic disks can not engage themselves.

08-30-2010 11:40 AM

Quote:

Originally Posted by Jeff
(Post 1628186)

It definitely looks like the brake fluid just ate the paint.

Brakes locking can be water in the system. The water sits in there and works similar to brake fluid when everything's cool. Then things get hot and the brakes start working and the water boils. Water turns into seam at a rate of something like 10,000:1 at atmospheric air pressure. So, the steam effectively applies the brakes by artificially increasing pressure in the braking system.

Sorry, but all my mechanical engineering courses say this ain't so!

Conventional glycol-based brake fluid is hygroscopic, which means that it absorbs water. This is important, in order to keep condensation in the brake system from causing corrosion. However, eventually, the fluid will absorb all the moisture it can hold, reaching its point of saturation. Several things can happen at this point. Unabsorbed moisture can begin to collect in the system, causing corrosion in critical areas; the water can cause seals to swell and deteriorate, further contaminating the fluid; and the boiling point of of the fluid drops beyond recommended levels. This means that under high-heat braking conditions, such as during hard braking or repeated brake application while descending a mountain, the fluid will start boiling sooner, which will reduce braking performance. The pedal can begin to feel spongy, and as braking efficiency drops, it takes longer to stop the vehicle.

Steam can not operate a hydraulic system. What is probably happening is that the seals are going bad expand enough to displace either the fluid or mechanical components to KEEP the brakes engaged after being used and then locking up...

john211

08-30-2010 11:49 AM

I dunno about the water theory. The actuator was locked in its nearly fully compressed extreme (about 3/16 inch away from the pin limiting out at the front end of the about 2-1/2 inch long slot). I could pull the trailer forward to the point of skidding the tires and the actuator wouldn't pull extended at all from where it was locked. As soon as we bled the brake fluid, it slid freely.

Jeff

08-30-2010 11:49 AM

Quote:

Originally Posted by SamIngram
(Post 1628226)

Sorry, but all my mechanical engineering courses say this ain't so!

Hmmm...... I was really just repeating something I had been told. I've never had first hand experience with them locking up due to moisture.

alans

08-30-2010 11:50 AM

Sam, good point. But what, then, would cause a linear increase in breaking pressure?

alans

08-30-2010 11:53 AM

John, that is strange, really strange.

08-30-2010 11:58 AM

They can lock due to moisture, the seals expand... Its a possibility that the fluid reached its point of saturation and the remaining water was then absorbed by the seals and locked the system...

The more probable reason is that the system was/is contaminated and the actuator locked as a result of expanding/bad seals. When he bled the system he reduced the overall pressure in the system letting the actuator break free. If this is case, when the actuator was changed I hope someone fully bled the system, otherwise another failure will probably happen again.

08-30-2010 11:59 AM

The solenoid could also be bad...

newty

08-30-2010 1:13 PM

Quote:

Originally Posted by SamIngram
(Post 1628236)

The solenoid could also be bad...

Kinda what I was thinking. It's not letting the cylinder pull the fluid back when the break is released after a stop.

Or... is the solenoid installed backwards or wrong solenoid hot to dis-engauge instead of hot to engauge?

Jeff

08-30-2010 1:24 PM

Is this on a MasterCraft trailer? They had some bad calipers that were notorious for locking up. Most people with affected trailers have gone to Kodiak calipers.

It's amazing what a couple shots of lube on the actuator keeps it freed up and prevents it from sticking an keeping the breaks applied.

john211

08-31-2010 9:01 AM

4 Attachment(s)

Never noticed before but, this thing disassembles ... like so. The solenoid looks fine. Itís halfway covered in a sock of like electric tape material. This could have so easily been re-built.

I know nothing about the calipers except the dealership and myself never suspected anything wrong with them (and do not today). This actuator was taken out of a 2004 Prestige trailer (for a 2006 Nautique 211. I have no idea why the trailer is two years older than the boat. It sure looked new when bought ... and Iím pretty sure it was at least un-used elsewhere. It was the license bureau told me about the age difference).

newty

08-31-2010 2:03 PM

From the looks of that solenoid I'll bet thats the problem. Effected either by heat or pressure.
Whats a new solenoid cost? That to me would be the only culprit, other than sticking brake cylinders.

Have you checked your wiring, and made sure your back-up lead isn't switched with something else or grounded?

john211

08-31-2010 2:23 PM

You know Newty, I couldn't reverse the trailer for the last 2 (of 4) years and always had to block the slide with bolts in the slot. I bet that solenoid had gone bad a long time ago. All seems solved now in Drive with the new actuator, but I will check the wiring condition for Reverse so as not to have another early failure of the solenoid.

And as I originally mentioned, getting less than 7,500 miles out of the tires burns me up just as much as the actuator.

08-31-2010 2:40 PM

The back-up solenoid valve is sold through Kodiak for about $50.

Take those four allen head screws off the cylinder and take a picture. Does it look like a regular brake cylinder? Just curious.

“The electrical lead from the solenoid valve (usually a blue wire) must be connected to the tow vehicles back-up lights. A ‘click’ should be heard when the tow vehicle is shifted into reverse and the back-up lights come on.”

I'll go out and listen for that click next time out. Here's what else the Buddy information says.

“This solenoid valve is fail-safe. That is, it will not open if it were to malfunction so the user will always have brakes when towing forward.”

OK .. so if it was malfunctioning and wouldn't open, could it trap pressurized brake fluid trapped behind it? I don't know. I'm giving up thinking about it. But I do see that all the parts are available. This could be easily re-built.

Hey Sam, in a day or two I'll post that picture you ask about. I'm curious too now.

I have a lot of the small parts for the UFP actuators if anyone needs some. I used to have UFP actuator, but I sold that boat and now have a different actuator.

john211

09-06-2010 5:28 PM

4 Attachment(s)

Last pics. After this, all gets re-cycled.

The bypass outlet for the solenoid valve is that pin-hole that is centered in the brass (or bronze) well (which the solenoid screws into). The bypass outletís valve-seat is that miniature conic boss which surrounds the centered pin-hole. The two larger holes are discharge end from the brake cylinder and intake to the brakes. Those holes are always open. The solenoid valve has a resilient (rubbery) dot which blocks flow of brake fluid into that pin-hole. Evidently, the pin-hole is always suctioning brake fluid into a bypass flow back into the reservoir. Therefore, the constant suction wants to hold the valve tight against the seat. However, when the solenoid is actuated (ie., when the voltage from the reverse lights energizes the solenoid), it lifts the valve off the seat Ė and hence a bypass flow back into the reservoir.

After examination, we found the following. The solenoid works. The brake fluid at that time was definitely water logged and was also contaminated with a lot of sludge. And then curiously, the piston in the brake cylinder was produced from a lightweight material which a magnet would not pick up. I guess aluminum but it was a strange material.

And so on. That guy with the Bryant boat definitely did not need to remove the whole actuator simply to replace the cable. That can be done without disassembling anything. But now I know, he did himself a big favor by changing his charge of brake fluid.

blake_hughes

09-06-2010 9:56 PM

Thanks for posting all the pics, that will be very helpful to a lot of people. I'm about to disassemble my trailer brake system this winter... I'm not looking forward to it.

cadunkle

09-07-2010 6:57 AM

Basically it's the same idea as rebuilding a master cylinder in a car. Kit is probably about $10 or $15 at most to go through that and replace all the rubber seals and such. Pretty straightforward if you're machanically inclined.

Jeff

09-07-2010 7:42 AM

Quote:

Originally Posted by cadunkle
(Post 1630595)

Kit is probably about $10 or $15 at most

Any ideas on where to actually get this? I've contacted UFP in the past about rebuild kits and they said they didn't offer them and the only solution was to replace the whole master cylinder.